Figure captions
Figure 1 Landscape site at Damxung County on the central
Tibetan Plateau and the pictures of the alpine steppes encroached (a) by
a leguminous shrub (Caragana spinifera ) and (b) by an
none-leguminous shrub (Dasiphora fruticosa ).
Figure 2 Differences in (a) vegetation cover (Cover), (b) plant
height (Height), (c) species richness (SR), (d) aboveground biomass
(AGB), (e) belowground biomass (BGB), (f) soil water content (SW), (g)
soil organic carbon content (SOC), (h) soil total nitrogen content
(STN), (i) soil microbial biomass carbon (MBC), (j) soil microbial
biomass nitrogen (MBN), (k) soil ammonia nitrogen
(NH4+−N), and (l) soil nitrate
nitrogen (NO3−−N) for the alpine
steppes encroached by a leguminous shrub (Caragana spinifera ) and
by an none-leguminous shrub (Dasiphora fruticosa ). Mean ± SD is
shown in error bars. Asterisks represent the significant differences
between the shrub encroached plots and non-shrub encroached plots. *p < 0.05; ** p < 0.01; *** p< 0.001.
Figure 3 Differences in the relative interaction intensity
(RII) values of individual ecosystem functions for the alpine steppes
encroached by (a) a leguminous shrub (Caragana spinifera ) and (b)
by an none-leguminous shrub (Dasiphora fruticosa ). Cover,
vegetation cover; Height, plant height; SR, species richness; AGB,
aboveground biomass; BGB, belowground biomass; SW, soil water content;
SOC, soil organic carbon content; STN, soil total nitrogen content; MBC,
soil microbial biomass carbon; MBN, soil microbial biomass nitrogen;
NH4+−N, soil ammonia nitrogen;
NO3−−N, soil nitrate nitrogen. Bars
indicated the SD of mean value. Asterisks represent the significant
differences between the shrub encroached plots and non-shrub encroached
plots. * p < 0.05; ** p < 0.01; ***p < 0.001.
Figure 4 Differences in (a) the ecosystem multifunctionality
(EMF), (b) aboveground ecosystem multifunctionality (AEMF), (c)
belowground ecosystem multifunctionality (BEMF) indexes between the
shrub encroached plots and non-shrub encroached plots and the relative
interaction intensity (RII) values of EMF, AEMF, and BEMF for the alpine
steppes encroached by (e) a leguminous shrub (Caragana spinifera )
and (f) by an none-leguminous shrub (Dasiphora fruticosa ). Bars
indicated the SD of mean value. Asterisks represent the significant
differences between the shrub encroached plots and non-shrub encroached
plots. * p < 0.05; ** p < 0.01; ***p < 0.001.
Figure 5 Correlation coefficients among the individual
ecosystem functions and multiple ecosystem functions relevant to the
ecosystem multifunctionality (EMF), aboveground ecosystem
multifunctionality (AEMF), belowground ecosystem multifunctionality
(BEMF) in the semi-arid alpine steppes. Cover, vegetation cover; Height,
plant height; SR, species richness; AGB, aboveground biomass; BGB,
belowground biomass; SW, soil water content; SOC, soil organic carbon
content; STN, soil total nitrogen content; MBC, soil microbial biomass
carbon; MBN, soil microbial biomass nitrogen;
NH4+−N, soil ammonia nitrogen;
NO3−−N, soil nitrate nitrogen. Bars
indicated the SD of mean value. Asterisks represent the significant
differences between the shrub encroached plots and non-shrub encroached
plots. * p < 0.05; ** p < 0.01; ***p < 0.001.
Figure 6 Correlation coefficients among the relative
interaction intensity (RII) values of individual ecosystem functions and
multiple ecosystem functions relevant to the ecosystem
multifunctionality (EMF), aboveground ecosystem multifunctionality
(AEMF), belowground ecosystem multifunctionality (BEMF) in respond to
shrub encroachment. Cover, vegetation cover; Height, plant height; SR,
species richness; AGB, aboveground biomass; BGB, belowground biomass;
SW, soil water content; SOC, soil organic carbon content; STN, soil
total nitrogen content; MBC, soil microbial biomass carbon; MBN, soil
microbial biomass nitrogen; NH4+−N,
soil ammonia nitrogen; NO3−−N, soil
nitrate nitrogen. Bars indicated the SD of mean value. Asterisks
represent the significant differences between the shrub encroached plots
and non-shrub encroached plots. * p < 0.05; ** p< 0.01; *** p < 0.001.
Figure 7 A schematic diagram for understanding the potential
ways of shrub encroachment on the individual ecosystem functions and
multiple ecosystem functions in the semi-arid alpine steppes.